The Murphy Builders Site

I've heard different opinions, but have occassionaly mixed them myself with no adverse results. Of course there are still some that say mogas is not good for your engine, while still others say it is better, because your oil will be cleaner and less chance of valve guide deposits. No expert myself, but have chosen to believe that mogas is OK. At the least, it should not cause sudden engine failure even it is a problem, and in the mean time I am saving gobs of money. At TBO, that would be over 20K savings for me, more than enough to pay for an overhaul. That made the choice easy for me.


If I had fuel injection, I might be concerned about vapour lock in heat and high altitudes, but I don't.

Walter

----- Original Message -----
From: Mike Kimball <mkimball@gci.net>
Date: Wednesday, December 15, 2004 1:59 pm
Subject: Avgas and Mogas use

I've read comments more than once about avgas in one tank and
mogas in the
other. This begs a question. What are the consequences of mixing
avgas and
mogas. I flew a C-152 with a mogas STC and had a mixture of avgas
and mogas
in the tanks and did not notice any problems. I also used mixed
fuel all
the time in my 912 powered Renegade. Are there problems that take
time to
develop?

Mike




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I've read comments more than once about avgas in one tank and mogas in the
other. This begs a question. What are the consequences of mixing avgas and
mogas. I flew a C-152 with a mogas STC and had a mixture of avgas and mogas
in the tanks and did not notice any problems. I also used mixed fuel all
the time in my 912 powered Renegade. Are there problems that take time to
develop?

Mike




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Walter,

I agree with you about the mogas avgas thing. I always run mogas even in
winter, except when I'm traveling, like last summer in BC, and it is not
convenient to use mogas or it's not available.

I am aware mogas can vapor lock and gum up when old and Lycoming says don't
do it for liability reasons. Even my Ellison Throttle Body carb says don't use
mogas but I have never had a problem with either and over the life of the
engine TBO you can save more than enough to pay for an overhaul.

Bruce








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I ran a C185 on mogas for 500+ hours and never had a problem. I am
curious as I am planning building a Moose with the V8 engine. I have
had several people tell me to only use a certified aircraft engine. I
had over 250,000 miles on my 79 Eldorado and from the time it was new,
never had a fuel problem. Figuring a speed average of 40 mph over the
250k miles is over 6000 hours. And is still running. Does this mean
that GM make a better motor that will run on a lesser gas for a longer
time, and cheaper to overhaul than Continental or Lycoming? Just food
for thought. But a V8 makes more sense to me.

Bobby

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of
Legeorgen@aol.com
Sent: Wednesday, December 15, 2004 11:54 PM
To: rebel-builders@dcsol.com
Subject: Re: Avgas and Mogas use

Walter,

I agree with you about the mogas avgas thing. I always run mogas even
in
winter, except when I'm traveling, like last summer in BC, and it is
not
convenient to use mogas or it's not available.

I am aware mogas can vapor lock and gum up when old and Lycoming says
don't
do it for liability reasons. Even my Ellison Throttle Body carb says
don't use
mogas but I have never had a problem with either and over the life of
the
engine TBO you can save more than enough to pay for an overhaul.

Bruce








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My main concern about mogas is the possibility of gumming, and I have had that happen in the past with boats and motorcyles that weren't used for a while. In my case, because I use that fuel flow sensor, I don't like to take the chance of that thing plugging or being a problem. So during the winter, or when I might not fly as frequently, that's when I run avgas. Also, on trips, as Bruce mentions, you often don't have a choice, so my plane still get its fair share of avgas in a year. I do stay away from alcohol fuels, though.

Walter

----- Original Message -----
From: Bobby Sather <sather@charter.net>
Date: Thursday, December 16, 2004 8:56 am
Subject: RE: Avgas and Mogas use

I ran a C185 on mogas for 500+ hours and never had a problem. I am
curious as I am planning building a Moose with the V8 engine. I have
had several people tell me to only use a certified aircraft
engine. I
had over 250,000 miles on my 79 Eldorado and from the time it was new,
never had a fuel problem. Figuring a speed average of 40 mph over the
250k miles is over 6000 hours. And is still running. Does this mean
that GM make a better motor that will run on a lesser gas for a longer
time, and cheaper to overhaul than Continental or Lycoming? Just food
for thought. But a V8 makes more sense to me.

Bobby

-----Original Message-----
From: mike.davis@dcsol.com [mike.davis@dcsol.com] On Behalf Of
Legeorgen@aol.com
Sent: Wednesday, December 15, 2004 11:54 PM
To: rebel-builders@dcsol.com
Subject: Re: Avgas and Mogas use

Walter,

I agree with you about the mogas avgas thing. I always run mogas even
in
winter, except when I'm traveling, like last summer in BC, and it is
not
convenient to use mogas or it's not available.

I am aware mogas can vapor lock and gum up when old and Lycoming says
don't
do it for liability reasons. Even my Ellison Throttle Body carb says
don't use
mogas but I have never had a problem with either and over the
life of
the
engine TBO you can save more than enough to pay for an overhaul.

Bruce








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Hi Walter !

What you are doing is very wise ! The old Lycomings & Continentals
don't have modern metallurgy anywhere - and the valve seats are particularly
vulnerable. This is where the lead comes in - it lubes the seats and prevents
the valves from spot-welding onto the seat ! I've seen several valves with
big chunks of seat stuck to them !!!

The O-320 (and most old engines) were designed for 80/87 Avgas -
100 LL has FOUR TIMES as much lead as 80/87 !! That's why we get
lead fouling on the plugs - and leaning at idle can help, if you're careful,
AND don't forget to go rich for takeoff !!

Old engines have a considerable amount of lead stored in the pores of
the metal, and it leaches out over time when you run mogas (unleaded),
providing some lubrication. This lead needs to be replenished by running
the odd (say -- 1 in 4 ) tankful of 100LL - either that, or you should add
some AVP or similar valve lubricant. Your alternating fuel usage should
serve you well !

I always ran 100LL in one tank, and Shell Bronze in the other - apparently
there are good reasons NOT to mix fuel types . They don't really mix evenly,
the mogas attracts more water, and can gum up, and there may be interactions
between additives. (This from an old pro in the fuel business ....)
(Shell - because they were the ONLY company that DIDN'T add alcohol !)

I know from experience that Mogas has changed drastically over the last
10 years - it doesn't have nearly the 'shelf life' it did have, and seems to
lose effectiveness much quicker. Also seems to have a larger proportion of
'oily' residue - likely things to satisfy the EPA, more than improve operation
of the engine. In the winter, they blend it to be much more volitile, for
easy starting, and add more alcohol to grab water, making it less desireable
for aircraft use. All good reasons to use 100LL in winter !

The savings in fuel costs is not enough to cover the costs of new cylinders
needed if a valve sticks - or much more damage if the engine quits !! The odd
tak of 100LL will help avoid this problem.

Also - those who are running Mogas - if you don't already, you can claim
a rebate of the 'Road Tax' included in the mogas price in most areas. In
Ontario, all you need is copies of your fuel receipts (in case they ask), and
send in an application with a photocopy of your log book pages. As long as
the fuel used matches (approx.) the hours flown, you get about 12 cents
a liter (!!!) as a refund !! Definitely worth asking for !

.......bobp

-------------------------------orig.-------------------------
On Thursday 16 December 2004 12:25 pm, WALTER KLATT wrote:

My main concern about mogas is the possibility of gumming, and I have had
that happen in the past with boats and motorcyles that weren't used for a
while. In my case, because I use that fuel flow sensor, I don't like to
take the chance of that thing plugging or being a problem. So during the
winter, or when I might not fly as frequently, that's when I run avgas.
Also, on trips, as Bruce mentions, you often don't have a choice, so my
plane still get its fair share of avgas in a year. I do stay away from
alcohol fuels, though.

Walter

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I miss using mogas. Over a twenty year period I used about 8 thousand
gallons of mogas in my Cherokee with an 0-320. Mostly hand carried onto the airport
in 5 gallon jugs with a savings of about a dollar a gallon.

In recent years only mogas containing up to 10% alcohol can be sold in gas
stations in the greater Chicago/Milwaukee area. This is because the area is
designated by the EPA as an air pollution "attainment area" and the alcohol
serves as an oxidizer and reduces tail pipe emissions. Few airports in Illinois
and Wisconsin sell mogas which of course has to be alcohol free.

Mogas provided for better winter starts and clean spark plugs.

Norm Wandke, R200 still under construction.




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Mogas has been manufactured under many different guide lines and formulas.
I have been reading this thread with alot of interest and must relate my
little experience with the stuff. I rebuilt an 0-235-C1- new valves, rings
etc and flew the first 25 hours with 100ll as suggested by ECI in Texas to
get a good buildup of lead in the sump. Used auto fuel for the next 50 and
started to notice leaky exhaust valves. Recut the seats and replaced
exhaust valves and used a mixture of av/auto fuel for the next 400 hrs
without a problem. Fueled from a barrel adding 50 liters of avgas and
topping it off with regular auto gas. Gives the right amount of lead as
80/87 use to have. A buddy of mine had his 172 0-320 rebuilt or overhauled;
I believe it was from Leavens in Ontario. Used nothing but auto gas and had
to do a complete top end in 300 hrs. All the valves were burned. Unless
you are getting the newer, better quality products from Superior or
Lycoming, I'd be inclined to have some lead in there. There is just too
many of the older engines out there with the softer valves. My 2 cents worth

Steve W.
Rebel 637

From: Newcog@aol.com
Reply-To: <rebel-builders@dcsol.com>
To: rebel-builders@dcsol.com
Subject: Re: Avgas and Mogas use
Date: Fri, 17 Dec 2004 11:24:55 EST

I miss using mogas. Over a twenty year period I used about 8 thousand
gallons of mogas in my Cherokee with an 0-320. Mostly hand carried onto
the airport
in 5 gallon jugs with a savings of about a dollar a gallon.

In recent years only mogas containing up to 10% alcohol can be sold in gas
stations in the greater Chicago/Milwaukee area. This is because the area is
designated by the EPA as an air pollution "attainment area" and the alcohol
serves as an oxidizer and reduces tail pipe emissions. Few airports in
Illinois
and Wisconsin sell mogas which of course has to be alcohol free.

Mogas provided for better winter starts and clean spark plugs.

Norm Wandke, R200 still under construction.




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I've been reading these threads with a lot of interest, as I'm considering
buying a moose kit. So what's the verdict with using Mogas in the M14P?
I've heard it works, but all this talk about burned valves worries me...

Second subject: Is the M14P a certified engine? I have no idea how to
tell...

Mark

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of steve
whitenect
Sent: Friday, December 17, 2004 20:43
To: rebel-builders@dcsol.com
Subject: Re: Avgas and Mogas use

Mogas has been manufactured under many different guide lines and formulas.
I have been reading this thread with alot of interest and must relate my
little experience with the stuff. I rebuilt an 0-235-C1- new valves, rings
etc and flew the first 25 hours with 100ll as suggested by ECI in Texas to
get a good buildup of lead in the sump. Used auto fuel for the next 50 and
started to notice leaky exhaust valves. Recut the seats and replaced
exhaust valves and used a mixture of av/auto fuel for the next 400 hrs
without a problem. Fueled from a barrel adding 50 liters of avgas and
topping it off with regular auto gas. Gives the right amount of lead as
80/87 use to have. A buddy of mine had his 172 0-320 rebuilt or overhauled;
I believe it was from Leavens in Ontario. Used nothing but auto gas and had
to do a complete top end in 300 hrs. All the valves were burned. Unless
you are getting the newer, better quality products from Superior or
Lycoming, I'd be inclined to have some lead in there. There is just too
many of the older engines out there with the softer valves. My 2 cents worth

Steve W.
Rebel 637

From: Newcog@aol.com
Reply-To: <rebel-builders@dcsol.com>
To: rebel-builders@dcsol.com
Subject: Re: Avgas and Mogas use
Date: Fri, 17 Dec 2004 11:24:55 EST

I miss using mogas. Over a twenty year period I used about 8 thousand
gallons of mogas in my Cherokee with an 0-320. Mostly hand carried
onto the airport in 5 gallon jugs with a savings of about a dollar a
gallon.

In recent years only mogas containing up to 10% alcohol can be sold in
gas stations in the greater Chicago/Milwaukee area. This is because the
area is designated by the EPA as an air pollution "attainment area" and
the alcohol serves as an oxidizer and reduces tail pipe emissions. Few
airports in Illinois and Wisconsin sell mogas which of course has to be
alcohol free.

Mogas provided for better winter starts and clean spark plugs.

Norm Wandke, R200 still under construction.




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My 2cents worth take it for what its worth
I used auto gas for years and several thousand hrs. in lycoming 0320,0360,
0540 250 horse and round engines. Although now I use only avgas of the
100LL verity.
Not because I feel I need to, but because I sell the stuff.
some things I learned:
1 don't buy auto gas made for winter use the vapor pressure is different
from summer gas

2 use only premium grade from a known distributor

3 don't use it in a new or overhauled engine until its had 100 hrs of avgas
in it(need to build up some lead in valve guides and seats)

4 test it for alcohol, use graduated beaker or test tube with 10 equal
marks
put water in to 1 mark, fill the other 9 with gas let sit for awhile if the
water increases, you have alcohol

5 run a tank of 100LL every once in a while to help keep the lead up in the
valves

6 don't park your airplane for any length of time with auto fuel in your
tanks
if your not going to fly for a couple of months get the auto fuel burned out
and put in 100LL
I did this for years in AG planes with out any problems. we did run 100LL at
the end of the season to clean out the mogas so not to have problems with it
setting all winter. avgas is great stuff to put in small engines(lawn mowers
and the like ) when storing for long periods of time as in winter close to
the 48 th. line around the world
I also ran a 0360 180 hp Cessna 170 on a lot of auto fuel. years back I flew
a pipeline in a 800 mile loop I would start with auto fuel,and 3 hours out
would stop and top off with 100LL then top again with auto fuel. when I sold
it it had 1300 hrs doing that and compresson was fine.
I can't say what it will do at altitude as far a vapor lock problems, in
those days I got a nose bleed at anything over 300 feet.
Keith Kinden
----- Original Message -----
From: "Bob Patterson" <beep@sympatico.ca>
To: <rebel-builders@dcsol.com>
Sent: Thursday, December 16, 2004 12:24 PM
Subject: Re: Avgas and Mogas use

Hi Walter !

What you are doing is very wise ! The old Lycomings & Continentals
don't have modern metallurgy anywhere - and the valve seats are

particularly

vulnerable. This is where the lead comes in - it lubes the seats and

prevents

the valves from spot-welding onto the seat ! I've seen several valves

with

big chunks of seat stuck to them !!!

The O-320 (and most old engines) were designed for 80/87 Avgas -
100 LL has FOUR TIMES as much lead as 80/87 !! That's why we get
lead fouling on the plugs - and leaning at idle can help, if you're

careful,

AND don't forget to go rich for takeoff !!

Old engines have a considerable amount of lead stored in the pores of
the metal, and it leaches out over time when you run mogas (unleaded),
providing some lubrication. This lead needs to be replenished by running
the odd (say -- 1 in 4 ) tankful of 100LL - either that, or you should

add

some AVP or similar valve lubricant. Your alternating fuel usage should
serve you well !

I always ran 100LL in one tank, and Shell Bronze in the other -

apparently

there are good reasons NOT to mix fuel types . They don't really mix

evenly,

the mogas attracts more water, and can gum up, and there may be

interactions

between additives. (This from an old pro in the fuel business ....)
(Shell - because they were the ONLY company that DIDN'T add alcohol !)

I know from experience that Mogas has changed drastically over the last
10 years - it doesn't have nearly the 'shelf life' it did have, and seems

to

lose effectiveness much quicker. Also seems to have a larger proportion of
'oily' residue - likely things to satisfy the EPA, more than improve

operation

of the engine. In the winter, they blend it to be much more volitile,

for

easy starting, and add more alcohol to grab water, making it less

desireable

for aircraft use. All good reasons to use 100LL in winter !

The savings in fuel costs is not enough to cover the costs of new

cylinders

needed if a valve sticks - or much more damage if the engine quits !! The

odd

tak of 100LL will help avoid this problem.

Also - those who are running Mogas - if you don't already, you can claim
a rebate of the 'Road Tax' included in the mogas price in most areas. In
Ontario, all you need is copies of your fuel receipts (in case they ask),

and

send in an application with a photocopy of your log book pages. As long as
the fuel used matches (approx.) the hours flown, you get about 12 cents
a liter (!!!) as a refund !! Definitely worth asking for !

.......bobp

-------------------------------orig.-------------------------
On Thursday 16 December 2004 12:25 pm, WALTER KLATT wrote:

My main concern about mogas is the possibility of gumming, and I have

had

that happen in the past with boats and motorcyles that weren't used for

a

while. In my case, because I use that fuel flow sensor, I don't like to
take the chance of that thing plugging or being a problem. So during the
winter, or when I might not fly as frequently, that's when I run avgas.
Also, on trips, as Bruce mentions, you often don't have a choice, so my
plane still get its fair share of avgas in a year. I do stay away from
alcohol fuels, though.

Walter

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To add a little more fuel to the fire :):):). Ben Visser, who was a
Shell fuel expert for decades said at a Sun & Fun seminar that if a new
or overhauled aircraft engine was operated for the first 300 hours on
100LL that it could be expected to go to TBO on auto fuel. Of course a
shot of lead once in a while can't hurt. Remember that 100LL has about
18 times the amount of lead we used to have in leaded auto fuel. A
banner tow operator told me they mixed 1/3 Avgas and 2/3 auto fuel and
regularly exceeded TBO by hundreds of hours. Of course, that was ideal
operating conditions.

Keith is correct that the vapor pressure of auto fuel is higher that
100LL and especially so in the winter when the volatility is stepped up
so your car will start. As he says, 100ll has a much longer stable
period - I have heard at least 6 months without question. A more
insidious issue is the poor storability of auto fuel. After cleaning 9
motorcycle carburetors one spring I make it a point to use Stabil (fuel
stabilizer) in auto fuel that will sit more than 2 months. Phil
Lockwood (the Rotax guru) told me that Stabil was fine for the Rotaxes
at least.
Ralph Baker



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Based on this most recent talk about mogas and valve wear, I
decided to give my engine builder in Kamloops a call, just to
confirm which valves were used when he did my last overhaul.
Anyway, good news is that he only uses the newer hardened sodium
thicker walled valves (he gave the part number, but can't
remember), which are better for mogas, so mine are good. He did
however still recommend occasional use of avgas, basically
exactly as Bob P. described. He said he has heard of people going
the whole tbo with just mogas, but says he has also seen damaged,
which he calls "pounded" valves due to mogas. He also said it was
OK, and actually recommended mixing mogas with some avgas.

He said some engines are better than others for using mogas. 0320
and 0470 are good, but 0200 not so good. Forgot to ask about the
0235 and 0540.

Anyway, thought I would pass this on as well. There are
definitely many different opinions on this subject, so again,
people will have to decide for themselves and take their chances.
I still like that $20K savings, but will continue using avgas
occasionally.

Walter

-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
Ralph Baker
Sent: Friday, December 17, 2004 6:16 PM
To: rebel-builders@dcsol.com
Subject: Avgas and mogas use


To add a little more fuel to the fire :):):). Ben
Visser, who was a
Shell fuel expert for decades said at a Sun & Fun
seminar that if a new
or overhauled aircraft engine was operated for the
first 300 hours on
100LL that it could be expected to go to TBO on auto
fuel. Of course a
shot of lead once in a while can't hurt. Remember
that 100LL has about
18 times the amount of lead we used to have in leaded
auto fuel. A
banner tow operator told me they mixed 1/3 Avgas and
2/3 auto fuel and
regularly exceeded TBO by hundreds of hours. Of
course, that was ideal
operating conditions.

Keith is correct that the vapor pressure of auto fuel
is higher that
100LL and especially so in the winter when the
volatility is stepped up
so your car will start. As he says, 100ll has a much
longer stable
period - I have heard at least 6 months without
question. A more
insidious issue is the poor storability of auto fuel.
After cleaning 9
motorcycle carburetors one spring I make it a point to
use Stabil (fuel
stabilizer) in auto fuel that will sit more than 2
months. Phil
Lockwood (the Rotax guru) told me that Stabil was fine
for the Rotaxes
at least.
Ralph Baker



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Realistically, how many of us are going to TBO or put 2000 hours on our
planes anyway? My flying may average 100 hours a year, at most, and from knowing
the friend I have who fly, they aren't much different.

That would make me 71 years old...oops, I'm not so young anymore, when it's
time to even consider an overhaul. I don't think that far in advance except
maybe my retirement. There are just to many variables in life.

Most of us who are using mogas have to settle for avgas periodically,
anyway, if we want to travel outside the pattern.

Walter, look what you got started with the mogas/avgas thing. It has been an
education for me. Now I know why my Rotax powered Kitfox with mogas quit on
approach to final and wouldn't idle after the mogas in it was 8 months old!!!
The landing was uneventful however.

Bruce




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Yup, gumming with old mogas is definitely a common problem. I
don't know what the 912 has for idle jets, but I would pull those
carb bowls and have a look.

Well, I sure hope I'm still flying when I'm 71. It always gives
me hope when I see some of the old geezers (oops, hope I didn't
offend anyone on the list) at my home field at Langley flying the
old warbirds and other high performance airplanes. And I can only
wish when I see how they fly, too. I am sure some of them are
close to 80.

Walter

-----Original Message-----
From: mike.davis@dcsol.com
[mailto:mike.davis@dcsol.com]On Behalf Of
Legeorgen@aol.com
Sent: Saturday, December 18, 2004 8:23 AM
To: rebel-builders@dcsol.com
Subject: Re: Avgas and mogas use


Realistically, how many of us are going to TBO or put
2000 hours on our
planes anyway? My flying may average 100 hours a year,
at most, and from knowing
the friend I have who fly, they aren't much different.

That would make me 71 years old...oops, I'm not so
young anymore, when it's
time to even consider an overhaul. I don't think that
far in advance except
maybe my retirement. There are just to many variables in life.

Most of us who are using mogas have to settle for
avgas periodically,
anyway, if we want to travel outside the pattern.

Walter, look what you got started with the mogas/avgas
thing. It has been an
education for me. Now I know why my Rotax powered
Kitfox with mogas quit on
approach to final and wouldn't idle after the mogas in
it was 8 months old!!!
The landing was uneventful however.

Bruce




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Yup gumming is a bad rap that comes mostly from 2 cycle mixed fuel IMO.
I definately add a stabilizer to mixed fuel if it is rarely used. Of
course we know their are other reasons (such as severe octane
degradation) to not fly with old mixed 2 cycle fuel.

Gumming is rare with straight gas and very rare if you drain the carb
before long periods of storage. Some white metal carb castings do
(catalytically??) hasten gumming quite a bit. I'll bet there was no need
to clean the fuel tanks on those 9 bikes. I store a hundred liters of
straight gas for 6 months at a time for the generator and don't even add
stabilizer. I do add stabilizer if the fuel is going to sit in a carb
that won't be drained for more than a month or two.

So far I've been able to avoid any experience with fuels containing
alcohol though.

Ken

Ralph Baker wrote:

To add a little more fuel to the fire :):):). Ben Visser, who was a
Shell fuel expert for decades said at a Sun & Fun seminar that if a new
or overhauled aircraft engine was operated for the first 300 hours on
100LL that it could be expected to go to TBO on auto fuel. Of course a
shot of lead once in a while can't hurt. Remember that 100LL has about
18 times the amount of lead we used to have in leaded auto fuel. A
banner tow operator told me they mixed 1/3 Avgas and 2/3 auto fuel and
regularly exceeded TBO by hundreds of hours. Of course, that was ideal
operating conditions.

Keith is correct that the vapor pressure of auto fuel is higher that
100LL and especially so in the winter when the volatility is stepped up
so your car will start. As he says, 100ll has a much longer stable
period - I have heard at least 6 months without question. A more
insidious issue is the poor storability of auto fuel. After cleaning 9
motorcycle carburetors one spring I make it a point to use Stabil (fuel
stabilizer) in auto fuel that will sit more than 2 months. Phil
Lockwood (the Rotax guru) told me that Stabil was fine for the Rotaxes
at least.
Ralph Baker

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